package com.zj.study.utils.util;

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.Optional;
import org.springframework.http.HttpHeaders;
import org.springframework.http.server.ServerHttpRequest;


/**
 * @author 赵赳
 * @since 2021/10/26 14:33
 */
public class IPUtils {

  private static final String IP_UNKNOWN = "unknown";
  private static final String IP_LOCAL = "127.0.0.1";
  private static final String IPV6_LOCAL = "0:0:0:0:0:0:0:1";
  private static final int IP_LEN = 15;


  /**
   * 获取用户真实IP地址，不直接使用request.getRemoteAddr();的原因是有可能用户使用了代理软件方式避免真实IP地址,
   *
   * 可是，如果通过了多级反向代理的话，X-Forwarded-For的值并不止一个，而是一串IP值，究竟哪个才是真正的用户端的真实IP呢？
   * 答案是取X-Forwarded-For中第一个非unknown的有效IP字符串。
   *
   * 如：X-Forwarded-For：192.168.1.110, 192.168.1.120, 192.168.1.130,
   * 192.168.1.100
   *
   * 用户真实IP为： 192.168.1.110
   *
   * @param request
   * @return
   */
  public static String getIpAddress(ServerHttpRequest request) {
    HttpHeaders headers = request.getHeaders();
    String ipAddress = headers.getFirst("x-forwarded-for");
    if (ipAddress == null || ipAddress.length() == 0 || IP_UNKNOWN.equalsIgnoreCase(ipAddress)) {
      ipAddress = headers.getFirst("Proxy-Client-IP");
    }
    if (ipAddress == null || ipAddress.length() == 0 || IP_UNKNOWN.equalsIgnoreCase(ipAddress)) {
      ipAddress = headers.getFirst("WL-Proxy-Client-IP");
    }
    if (ipAddress == null || ipAddress.length() == 0 || IP_UNKNOWN.equalsIgnoreCase(ipAddress)) {
      ipAddress = Optional.ofNullable(request.getRemoteAddress())
          .map(address -> address.getAddress().getHostAddress())
          .orElse("");
      if (IP_LOCAL.equals(ipAddress)|| IPV6_LOCAL.equals(ipAddress)) {
        // 根据网卡取本机配置的IP
        try {
          InetAddress inet = InetAddress.getLocalHost();
          ipAddress = inet.getHostAddress();
        } catch (UnknownHostException e) {
          // ignore
        }
      }
    }

    // 对于通过多个代理的情况，第一个IP为客户端真实IP,多个IP按照','分割
    if (ipAddress != null && ipAddress.length() > IP_LEN) {
      int index = ipAddress.indexOf(",");
      if (index > 0) {
        ipAddress = ipAddress.substring(0, index);
      }
    }
    return ipAddress;
  }


}
